1. Field
One or more embodiments of the present invention relate to a speaker array system including a plurality of speakers and a signal processing method used by the speaker array system, and more particularly, to a method and apparatus for compensating for a near-field effect in which a sound output from a speaker array is distorted when a listener moves close to the speaker array, wherein the apparatus is included in a speaker array system.
2. Description of the Related Art
A speaker array including a plurality of speakers is used to control the direction of a sound, which is to be reproduced by the speaker array, or send the sound to a specific region. In order to direct a sound toward a target position or in a target direction, an array including a plurality of sound sources is required. A sound propagation principle, called “directivity,” is directed to overlapping a plurality of sound signals using phase differences between them so as to increase signal intensity in a specified direction and transmit the sound signals in the specified direction. Therefore, directivity can be achieved by controlling sound signals which are output from a plurality of speakers arranged at predetermined positions.
When sound signals are output from a speaker array, the sound signals radiated from a plurality of speakers in the speaker array distort each other in a region within a predetermined distance away from the speaker array. Thus, non-uniform radiation characteristics of the sound signals are found in this region. This phenomenon, which is called “near-field effect,” occurs because the individual sound signals radiated from the speakers cannot form respective sound fields near the speaker array.
As used herein, the term “sound source” denotes a source which radiates sounds, that is, an individual speaker included in a speaker array. In addition, the term “sound field” denotes a virtual region formed by a sound which is radiated from a sound source, that is, a region which sound energy reaches. The term “sound pressure” denotes the power of sound energy which is represented using the physical quantity of pressure.